Google is getting serious about its Google Express same-day delivery service, adding more cities and merchants along with a monthly subscription charge.

The search giant gets serious about same-day delivery.

Google is getting serious about its Google Express same-day delivery service, adding more cities and merchants along with a monthly subscription charge.

The service, formerly known as Google Shopping Express, is expanding to Chicago, Boston and Washington D.C., after previous launches in San Francisco, San Jose, Manhattan, and West Los Angeles.

To place an order, users must shop through Google's website, which links to more than three dozen retailers. Users must then purchase at least $15 worth of goods and choose from morning, afternoon or evening delivery windows. (Overnight delivery is also available in Northern California.)

Although Google has always planned to charge a subscription fee, the company is only now setting a price of $10 per month or $95 per year. Alternatively, users can pay $5 for individual orders. Google is also shortening the free trial period from six months to three months.

To make the service more worthwhile, Google has signed on 16 new retailers over the last few months, including Barnes & Noble, PetSmart, Vitamin Shoppe, and Sports Authority. Google is also adding alcohol to its approved items list in in the Bay Area, as long as the buyer is at least 21 years old.

The story behind the story: Just as Google was making this announcement, Executive Chairman Eric Schmidt was calling out Amazon as Google's biggest competitor in search. He noted that more than twice as many people looking to buy something started on Amazon as opposed to Google last year, and that's obviously something Google would like to change.

It's probably no coincidence that Google Express' pricing is nearly identical to that of Amazon Prime. And if we were to speculate, the idea of Google someday tying in free books, music or video with an Express subscription doesn't seem too far-fetched.